The MIOConsole3d Application
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MADI sample rate formats
There are two ways 3d references sample rate for MADI:
‘
Base
’ reads the audio stream sample rate as the 1x ‘Base’ rate, where 44.1kHz is the ‘Base’ sample rate for
streams carrying 88.2kHz(2x) and 176.4kHz(4x) audio data, and 48kHz is the ‘Base’ rate for 96kHz(2x) and
192kHz(4x) audio. The audio data frame doubles in size with each multiplier, which consequently halves
the number of audio channels with each multiplier. This is the same as the ‘Dual-Wire’ and ‘Quad-Wire’
configurations used to carry AES audio data back in the ‘90’s, when digital I/O chipsets could only handle
44.1k and 48k sample rates.
Base
is generally the place to start for 44.1kHz and 48kHz, and may be required
for decoding “SMUX'd” high sample rate streams.
Native
is (again, generally) used at high sample rates and frames the audio at the ‘actual’ or ‘native’ rate,
so ‘Native’ 96kHz sample rate is actually read as 96kHz and so on.
At 1x rates,
Base
and
Native
are the same.
MADI frame/channel formats
‘
Legacy
’ is the older 56 channel frames format, where at 1x sample rates you get 56 channels, 2x you get
28 channels and 4x gets you 14 channels.
‘
Long
’ is the more recent 64 channel frames format, where at 1x sample rates you get 64 channels, at 2x
you get 32 channels and 4x gets you 16 channels.
Some manufacturers may exclusively use the ‘Legacy’ 56-channel format, some only use ‘Long’. With newer
gear, try ‘Long’ first.
In practice, you always want to use Word Clock to sync MADI transfers. Word Clock is a requirement in
the MADI spec. But even with great word clock, and especially when dealing with gear from the ‘90’s
and ‘00’s, clean MADI lock can sometimes be a bit of trial and error. One piece of gear may not handle
‘Native’ frame rates at 4x, so you try ‘Base’, and hey, if it works it works, don‘t complain. Another prominent
manufacturer may not support ‘Base’ frames or SMUX at all. The key here is compatibility, and between
the ‘Base/Native’ and ‘Legacy/Long’ formats controls you should be able to communicate perfectly with
any MADI gear you come across.
To that end, 3d MADI has been tested with some pretty cantankerous old beasts. Below is a first-generation
ULN-2, updated to 3d with a copper/optical MADI EdgeBus card, slaved to the MADI stream of a stock
Sony 3348HR at 44.1kHz. Solid as a rock. Of course, for the real transfers the 3348HR was slaved to the
3d word clock.
Figure 10.85: Test session: first-generation ULN-2 with 3d MADI clocked and locked to Sony 3348HR
